Embodiments described herein relate generally to the parenteral procurement of bodily fluid samples, and more particularly to devices and methods for parenterally procuring bodily fluid samples with reduced contamination from microbes and for verifying the bodily fluid sample volumes.
The in vitro diagnostics industry has expanded the types of approaches employed to identify, categorize, type, determine sensitivity and susceptibility (e.g., to specific antibiotics), and/or to otherwise discern desired information about bodily fluid samples with increased speed, specificity, and accuracy. For example, some such approaches include DNA/RNA sequencing, biological marker identification, mass spectrometry, centrifuging, magnetic separation, microfluidic isolation, molecular analysis, polymerase chain reaction (PCR) analysis, whole blood analysis, and/or the like. In some instances, such approaches can be used, for example, in microbial testing of parenterally obtained bodily fluids to determine the presence of one or more potentially undesirable microbes, such as bacteria, fungi, or yeast (e.g., Candida).
In some instances, microbial testing may include diagnostic methods including but not limited to incubating patient samples in one or more sterile vessels containing culture media that is conducive to microbial growth, molecular sample analysis, gene sequencing, PCR-based approaches, mass spectrometry, and/or the like, as noted above. Generally, when such microbes are present in the patient sample, the microbes flourish over time in the culture medium or can be detected and/or identified by one of the aforementioned technological approaches. When culture medium is utilized for microbial testing, after a variable amount of time (e.g., a few hours to several days), organism growth can be detected by automated, continuous monitoring (e.g., by detecting carbon dioxide and/or the like). The culture medium can then be tested for the presence of the microbes, which if present, suggests the presence of the same microbes in the patient sample and thus, in the bodily fluid of the patient from which the sample was obtained. When other technologies are used for microbial testing, the amount of time required to determine a presence of microbes may vary (e.g. from nearly instantaneously to several minutes, hours, or days). These technologies, however, are still sensitive to the inherent quality and/or integrity of the specimen that is being analyzed. Accordingly, when microbes are determined to be present in the culture medium or identified by another diagnostic test, the patient may be prescribed one or more antibiotics or other treatments specifically designed to treat or otherwise remove the undesired microbes from the patient.
Patient samples, however, can become contaminated during procurement and/or otherwise can be susceptible to false positive results. For example, microbes from a bodily surface (e.g., dermally-residing microbes) that are dislodged during needle insertion into a patient, either directly or indirectly via tissue fragments, hair follicles, sweat glands, and other skin adnexal structures, can be subsequently transferred to a culture medium with the patient sample and/or included in the specimen that is to be analyzed for non-culture based testing. Another possible source of contamination is from the person drawing the patient sample. For example, a doctor, phlebotomist, nurse, etc. can transfer contaminants from their body (e.g., finger, arms, etc.) to the patient sample and/or to the equipment containing the patient sample. Specifically, equipment and/or devices used during a patient sample procurement process (e.g., patient to needle, needle/tubing to sample vessels, etc.) often include multiple fluidic interfaces that can each introduce points of potential contamination. In some instances, such contaminants may thrive in a culture medium and/or may be identified by another diagnostic technology and eventually yield a positive microbial test result, thereby falsely indicating the presence of such microbes in vivo.
In some instances, false positive results and/or false negative results can be attributed to a specific volume of the patient sample. For example, some in vitro diagnostic (IVD) tests are sensitive to the ratio between bodily fluid collected in the sample reservoir and the preexisting contents in the sample reservoir which could include culture medium, additives (such as those described herein), and/or the like that are placed into the sample reservoir during manufacturing. In these instances, accurate results of the IVD test may depend on an appropriate amount of bodily fluid collected in the sample reservoir. For example, overfilling of volume-sensitive blood culture bottles can lead to false positive results as noted in the instructions for use and/or warning labeling from manufacturers of such culture bottles, as well as associated automated continuous monitoring microbial detection systems. On the other hand, insufficient patient sample volume within a culture medium can result in false negative results. By way of example, in a study performed by the Mayo Clinic entitled, Optimized Pathogen Detection with 30- Compared to 20-Milliliter Blood Culture Draws, Journal of Clinical Microbiology, December 2011, a patient sample volume of 20 milliliters (mL) can result in detection of about 80% of bacteremias present in a patient sample, a patient sample volume of 40 mL can result in detection of about 88% of the bacteremias, and a patient sample volume of 60 mL can result in detection of about 99% of the bacteremias. In some instances, such as in patients with sepsis, a concentration of colony forming units (CFUs) in the septic patient's bloodstream can be highly variable (including very low levels of less than 1 CFU per 10 ml of blood). Thus, ensuring that a sufficient amount of blood is collected and analyzed is desired for clinical confidence in the accuracy of the microbial test result.
While placing blood in a culture medium is a ‘standard of care’ today, a number of new technologies (examples of which are noted above) hold promise in increasing the pace with which microbes (and antibiotic susceptibility and/or sensitivity) can be identified in a bodily fluid sample. However, procuring a sufficient volume of blood that is analyzed remains desirable as a small volume of blood may not contain a CFU or other critical identifiable cell, biomaterial, compound, marker, organism, or the like that is actually present in the patient's bloodstream, thereby falsely indicating that a patient is not septic.
Such inaccurate results because of contamination, insufficient patient sample volume, and/or the like are a concern when attempting to diagnose or treat a suspected illness or condition. For example, false negative results from microbial tests may result in a misdiagnosis and/or delayed treatment of a patient illness, which, in some cases, could result in the death of the patient. Conversely, false positive results from microbial tests may result in the patient being unnecessarily subjected to one or more anti-microbial therapies, which may cause serious side effects to the patient including, for example, death, as well as produce an unnecessary burden and expense to the health care system due to extended length of patient stay and/or other complications associated with erroneous treatments. Additionally, the use of diagnostic imaging equipment attributable to these false positive results is also a concern from both a cost as well as patient safety perspective given the additional diagnostic procedures that are performed, potential for additional false positive or false negative results, as well as concerns around unnecessary exposure to concentrated radiation associated with a variety of imaging procedures (e.g., CT scans) has many known adverse impacts on long-term patient health.
As such, a need exists for sterile bodily fluid collection devices and methods that reduce microbial contamination in bodily fluid test samples. Additionally, a need exists for such bodily fluid collection devices to include a means for accurately verifying, measuring, and/or otherwise assessing and confirming a volume of bodily fluid transferred from a patient to a sample reservoir or culture medium that can be communicated via visual, tactile, or other means to a healthcare practitioner procuring the patient sample in substantially real-time (e.g. at the patient bedside, in an outpatient clinic or the like).